1. Field of the Invention
This invention relates to a rear wheel suspension apparatus for a motorcycle by which the height of the motorcycle can be adjusted.
2. Description of Background Art
A rear wheel suspension apparatus for a motorcycle is disclosed in Japanese Patent Laid-open No. Hei 5-16639 wherein an upper-end mounting portion of a rear shock absorber is driven by a motor to move in forward and backward directions to vary the mounting position of the rear shock absorber to adjust the height of the motorcycle.
Another rear wheel suspension apparatus for a motorcycle is disclosed in Japanese Patent Laid-open No. Sho 61-122089 wherein a connecting shaft between a first link arm on a body frame side and a second link arm on a rear swing arm side, which constitute a link of the rear wheel suspension apparatus, is coupled to a lower end portion of a rear shock absorber by way of an eccentric member wherein the connection point is manually adjusted to vary the link ratio and adjust the height of the motorcycle.
If an actuator is provided on an upper end portion side of a rear shock absorber as in Japanese Patent Laid-open No. Hei 5-16639, the actuator is always acted upon by a load from the rear wheel side, and as a result, the actuator must be relatively large and heavy to withstand this repeated stress. Because Japanese Patent Laid-open No. Sho 61-122089 involves manual adjustment, the operation is so complicated and cumbersome that it is impossible to rapidly adjust the height of the motorcycle while driving.
Depending upon the driver, however, it is sometimes desirable to adjust the height of the motorcycle while driving in order to make the height of the motorcycle suitable for the road on which the motorcycle is running. With the rear wheel suspension apparatus of Japanese Patent Laid-open No. Sho 61-122089 described above, however, it is impossible to perform height adjustment while the driver remains on the motorcycle. Also, a suspension structure that can maintain an ideal load characteristic even when the height of the motorcycle adjustment is demanded.